The goal of this project is to develop a sonar system that can be used as a mobility aid by the visually impaired. The system will consist of an ultrasonic acoustic source using a waveform that is designed to optimize target discrimination and a pair of miniature microphones that are mounted near the ears to create natural interaural level and timing differences. A heterodyning technique will be used to shift the signals received by the microphones down to the audible range after which it will be presented to the user through open-canal earphones. The acoustic source and microphone arrays will be mounted on the users head so that they can scan their environment with the sonar system using natural head movements. The specific aims of this Phase I STTR proposal include constructing a semi-portable prototype and a series of experiments designed to demonstrate the usefulness of the device. PUBLIC HEALTH RELEVANCE: This research will lead to a new mobility aid for the visually impaired. It will also help shed light on how visually impaired subjects might be taught use unaided echolocation to navigate through complex environments.